This section provides background information related to the present disclosure which is not necessarily prior art.
Work and life of people are changed greatly by development of the Internet technologies. Video communication technology enables persons separated by thousands of miles to obtain a face-to-face communication experience. Therefore, the video communication technology has been widely used in video chatting, video conference, network game, and so on.
Since the large amount of raw video data necessary to be processed in the video communication, it is necessary to perform video encoding on the raw video data before transmission, and then to generate a video bit-stream meeting certain requirements by setting encoding parameter, such as resolution, frame-rate and bit-rate, for a video encoder. At the receiving terminal, decoded video images may be obtained by decoding the video bit-stream. As to a fixed video codec, a video sequence is encoded with certain encoding parameters, and a relationship between the bit-rate and distortion may be obtained to serve as rate-distortion characteristic of the codec. The rate-distortion characteristic is generally used to describe decoded video quality corresponding to the bit-stream generated by the codec in conditions of different bit-rates.
In one-to-one network video communication, encoding parameters and transmission technologies are generally adjusted self-adaptively according to network status, so as to adapt to fluctuation of network bandwidth and improve transmitted video quality. In the process of multi-person video communication, since there are heterogeneity and time-varying property of status of a network connecting multiple subscribers, and processing capabilities of terminal devices (e.g., mobile phone and personal computer) are also different, the encoding parameters are set for video encoding and decoding according to average or major requirements traditionally, and a single bit-stream may be generated after encoding the raw video data. The single bit-stream may be broadcast for all the subscribers participating in a communication, and all the receiving remote clients may possess same video quality for the same video source being sent.
The multi-person video communication technology with single bit-stream broadcast can not adapt to variety of terminal processing capability and network status, for a subscriber with better network status and stronger terminal device processing capability, resources will be wasted and optimal video communication quality will not be achieved. While for a subscriber with worse network status and lower terminal processing capability, status, such as network congestion or terminal device cannot perform processes normally, will be caused.